
//计算经纬
export function calculateDistance(lat1: number, lon1: number, lat2: number, lon2: number): number {
    const R = 6371; // 地球半径，单位为千米
    const dLat = deg2rad(lat2 - lat1);
    const dLon = deg2rad(lon2 - lon1);
  
    const a =
      Math.sin(dLat / 2) * Math.sin(dLat / 2) +
      Math.cos(deg2rad(lat1)) * Math.cos(deg2rad(lat2)) *
      Math.sin(dLon / 2) * Math.sin(dLon / 2);
  
    const c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
    const distance = R * c;
  
    return distance;
  }
  
  function deg2rad(deg: number): number {
    return deg * (Math.PI / 180);
  }